NMNAT1 mutations cause Leber congenital amaurosis

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Leber congenital amaurosis (LCA) is an infantile-onset form of inherited retinal degeneration characterized by severe vision loss1,2. Two-thirds of LCA cases are caused by mutations in 17 known disease-associated genes3 (Retinal Information Network (RetNet)). Using exome sequencing we identified a homozygous missense mutation (c.25G>A, p.Val9Met) in NMNAT1 that is likely to be disease causing in two siblings of a consanguineous Pakistani kindred affected by LCA. This mutation segregated with disease in the kindred, including in three other children with LCA. NMNAT1 resides in the previously identified LCA9 locus and encodes the nuclear isoform of nicotinamide mononucleotide adenylyltransferase, a rate-limiting enzyme in nicotinamide adenine dinucleotide (NAD+) biosynthesis4,5. Functional studies showed that the p.Val9Met alteration decreased NMNAT1 enzyme activity. Sequencing NMNAT1 in 284 unrelated families with LCA identified 14 rare mutations in 13 additional affected individuals. These results are the first to link an NMNAT isoform to disease in humans and indicate that NMNAT1 mutations cause LCA.

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Figure 1: Pedigrees of three unrelated kindreds with LCA in which mutations were identified in NMNAT1.
Figure 2: Retinal image from individual with LCA due to mutations in NMNAT1.
Figure 3: NMNAT1 enzyme activity and cellular NAD+ content.

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We thank M. Sousa, D. Harnley, M.-E. Lancelot and A. Antonio for their excellent technical assistance, The Children's Hospital of Philadelphia CytoGenomics Laboratory for assistance with the establishment of the fibroblast cell lines and tissue culture and J. Baur for his helpful discussions on NAD+ metabolism. We are grateful to the individuals with LCA and their relatives for their participation in this study.

This work was supported by grants from the US National Institutes of Health (RO1-EY12910 (E.A.P.), R03-DK082446 (M.J.F.), R01-GM097409 (E.N.-O.), P30HD026979 (M.J.F. and R.X.) and P30EY014104 (Massachusetts Eye and Ear Infirmary core support)); the Foundation Fighting Blindness USA (I.A., A.D.B., E.L.B., S.S.B., Q.L., A.T.M., D.S.M., E.A.P., J.-A.S., S.M.-S. and A.R.W.); the Rosanne Silbermann Foundation (E.A.P.); the Penn Genome Frontiers Institute (E.A.P. and X.G.); the Institutional Fund to the Center for Biomedical Informatics by the Loyola University Stritch School of Medicine (X.G.); the Foerderer Award for Excellence from the Children's Hospital of Philadelphia (M.J.F. and X.G.); the Angelina Foundation Fund from the Division of Child Development and Metabolic Disease at the Children's Hospital of Philadelphia (M.J.F.); the Clinical and Translational Research Center at the Children's Hospital of Philadelphia (UL1-RR-024134) (M.J.F. and E.A.P.); the Department of Biotechnology, the Government of India and the Champalimaud Foundation, Portugal (C.K.); the Hyderabad Eye Research Foundation (C.K.); a senior research fellowship from the Council for Scientific and Industrial Research (R.S.); the Foundation Voir et Entendre, Ville de Paris and Région Ille de France (C.Z.); RP Fighting Blindness (UK)(A.R.W.); Fight For Sight (UK) (A.D.B., S.S.B., A.T.M., D.S.M. and A.R.W.); Moorfields Eye Hospital National Institute of Health Research (NIHR) British Research Council (BRC) for Ophthalmology (A.D.B., S.S.B., A.T.M., D.S.M. and A.R.W.); and the Special Trustees of Moorfields Eye Hospital (A.D.B., S.S.B., A.T.M., D.S.M. and A.R.W.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding organizations or the National Institutes of Health. This project is funded, in part, by the Penn Genome Frontiers Institute under a grant with the Pennsylvania Department of Health, which disclaims responsibility for any analyses, interpretations or conclusions.

Author information

Experiments were designed by Q.Z., M.J.F., X.G. and E.A.P. LCA case samples and controls were provided by I.A., A.D.B., E.L.B., S.S.B., C.K., M.J.F., S.J., A.T.M., E.P., S.M.-S., J.-A.S., A.R.W. and E.A.P. Pedigrees were compiled by A.D.B., C.C., C.K., S.J. and E.P. Individuals III-4, III-5, IV-1, IV-2 and IV-3 were clinically evaluated by M.J.F. and E.A.P. (individuals III-3, III-6 and IV-4 to IV-7 were not clinically evaluated by the authors). Exome sequencing was performed by M.C. Bioinformatics pipeline development was performed by X.G., M.J.F., E.A.P. and M.C. Exome data analyses were performed by J.C.P., X.G., Z.F.-K. and E.A.P. NMNAT1 sequencing and segregation analyses were performed by I.A., C.C., M.C., Z.F.-K., D.S.M., L.P., R.S., N.H.W., C.Z. and Q.Z. High-performance liquid chromatography (HPLC)-based NMNAT enzyme activity assay and NAD+ content assay development was performed by E.N.-O., with data analysis performed by E.N.-O., M.J.F., E.A.P. and R.X. In vitro functional studies were carried out by Q.Z., E.N.-O., J.O., Q.L. and M.S. The manuscript was written by M.J.F., Q.Z., X.G. and E.A.P.

Correspondence to Eric A Pierce.

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Falk, M., Zhang, Q., Nakamaru-Ogiso, E. et al. NMNAT1 mutations cause Leber congenital amaurosis. Nat Genet 44, 1040–1045 (2012) doi:10.1038/ng.2361

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